This invention relates to a track unit usable on a vehicle for tractive engagement with the terrain surface, for thereby moving the vehicle along the terrain surface. Track units of this invention are especially designed for use on military tanks and personnel carriers.
The term "track unit" is here used to mean one section of an endless terrain-engagement assembly. Usually two such assemblies are used per vehicle, one assembly at the right side of the vehicle and another assembly at the left side of the vehicle.
A large number of individual track units (e.g. seventy five) are linked together to form one endless track assembly. Each assembly is trained around a drive sprocket at one end of the vehicle, an idler wheel at the other end of the vehicle, and a series of ground wheels spaced along the length of the vehicle.
Each individual track unit comprises an upstanding prong designed to enter grooves in the ground wheels to prevent lateral dislocation of the endless assembly from its designed operating plane. Openings are provided along side edge areas of the endless track assembly to accommodate teeth on the drive sprocket(s). Each drive sprocket mechanism comprises two axially-spaced sprocket wheels affixed to a common hub structure carried on an output shaft of the vehicle power plant.
My invention is concerned with the design of an individual track unit. The individual unit is of the "double pin" type, i.e. a track unit having a transverse pin at each of its ends. The pins on adjacent track units are connected by rigid links bridging the space between the track units.
Each track pin is mounted within an oversize bore in the associated track unit. An annular bushing of elastomeric material is packed around each pin to form a torsional connection between the pin and track unit.
Each elastomeric bushing seals the joint between the track pin and bore surface, such that dirt or moisture is prevented from entering into the joint and thereby producing excessive track pin wear or deterioration.
Some objects of my invention are to provide a double pin track unit wherein:
1. the track pin bushings have relatively large cylindrical surface areas. PA0 2. the pin bushings are subjected to relatively low unit area forces in radial directions. PA0 3. the track pad has a relatively large face area. PA0 4. the track pad is subjected to relatively low unit area forces in directions normal to the terrain. PA0 5. the track pad has a relatively long service life. PA0 6. the track unit has no end connectors. PA0 7. the links between adjacent track units are of unitary one-piece design. PA0 8. the track-connection links have strong drive engagements with the associated track pins. PA0 9. the track-connection links are subjected primarily to tensile loadings rather than bending forces. PA0 10. the track body is a unitary one piece unit that defines surfaces at its outer edges for engaging sprocket teeth and includes an upstanding guide (prong) on its centerline for engaging ground wheels. PA0 11. the tooth engaging surfaces on the track body have high-strength connections with the main section of the track body.